Sensory evaluation, chemical structures, and threshold concentrations of bitter-tasting compounds in common foodstuffs derived from plants and maillard reaction: A review.

The bitterness of foodstuffs is often associated with toxicity, which negatively influences product acceptability. However, bitter compounds have many benefits, and a slight bitter taste is sometimes favored. In this review, we summarize the methods used to isolate and evaluate the taste of bitter compounds in different foods. The chemical structures and threshold concentrations of these compounds are also recapped. Although the structures and thresholds of many bitter compounds have been confirmed, further studies are needed to develop detailed bitter-masking strategies and establish the relation between functional groups (hetero-cyclic substituents and bonding types) and taste quality. Furthermore, a comprehensive bitterness database and chemometric data must be provided in order to quickly assess the bitterness of unfamiliar products.

Effects of moisture content on the enolization products formation in glucose-proline Maillard reaction models.

BACKGROUND: 2,3-Dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one (DDMP) and 5-hydroxymethylfurfural (HMF) are two main enolization products in the Maillard reaction and found in some foodstuffs. For many years, whether they are functional or noxious to human health has been a matter of debate. Thus, insight into their formation pathways is important to manage Maillard reaction products. In this study, DDMP and HMF were quantified and compared with regard to their formation and degradation in the d-glucose and l-proline Maillard reaction models using different moisture contents (0, 0.1, 0.5, 1.0, and 4.0 mL) at 150 °C for various heating times. RESULTS: DDMP was predominantly generated in dry or low water-content heating models along with n increased 1-deoxyglucosone (1-DG) generation via 2,3-enolization. However, increasing moisture content resulted in a decay of reaction intensity, 1-DG, and DDMP due to a change in the reaction mechanism from 2,3-enolization to 1,2-enolization, which facilitated 3-deoxyglucosone (3-DG) and HMF formation. CONCLUSION: Increased moisture content in glucose-proline models reduced reaction intensity and also inhibited DDMP and facilitated HMF formation by promoting the pathway change from 2,3-enolization to 1,2-enolization to generate more 3-DG. A water content of 1.0 mL was identified as a critical value, from which the 1,2-enolization became a primary pathway occurring in the Maillard reaction. © 2022 Society of Chemical Industry.

Thiophene enantiomers from the aerial parts of Eclipta prostrata.

Ten thiophene derivatives (1-10), including two previously undescribed ones (1 and 2), have been obtained and structurally characterized from the aerial parts of a traditional Chinese herb Eclipta prostrata. Six of them with one chiral center were identified to be scalemic mixtures, and the pure enantiomers of two isolates (1 and 3) were successfully separated via chemical derivatization and chiral HPLC, with the absolute configurations being established by analysis of optical rotations. All the thiophenes were subjected to a series of assays and compounds 9 and 10 exhibited mild antibacterial activity against Staphylococcus aureus.[Formula: see text].

Structural characterization and biological evaluation of chemical constituents from Ilex cornuta.

One new ursane-type triterpenoid (1), one new ursane-type triterpenoid glycoside (2), and one new oleanane-type triterpenoid glycoside (3), along with 20 known compounds, were isolated from the leaves of Ilex cornuta. The structures of these natural products were elucidated on the basis of detailed spectroscopic analyses and chemical derivation. Our biological evaluation established that selective compounds showed moderate to significant antioxidant activities in the 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) methods.

New e:b-Friedo-Hopane Type Triterpenoids from Euphorbia peplus with Simiarendiol Possessing Significant Cytostatic Activity against HeLa Cells by Induction of Apoptosis and S/G2 Cell Cycle Arrest.

Seven rare e:b-friedo-hopane-type triterpenoids including four new (1-4) and three known (5-7) ones with 5 being first reported as a natural product, together with five other known triterpenoids (8-12), were isolated from the nonpolar fractions of the ethanolic extract of Euphorbia peplus. Structural assignments for these compounds were based on spectroscopic analyses and quantum chemical computation method. The structural variations for the C-21 isopropyl group, including dehydrogenation (1 and 3) and hydroxylation at C-22 (simiarendiol, 2), were the first cases among e:b-friedo-hopane-type triterpenoids. Simiarendiol (2) bearing a 22-OH showed significant cytostatic activity against HeLa and A549 human tumor cell lines with IC50 values of 3.93 ± 0.10 and 7.90 ± 0.31 µM, respectively. The DAPI staining and flow cytometric analysis revealed that simiarendiol (2) effectively induced cell apoptosis and arrested cell cycle at the S/G2 phases in a dose-dependent manner in HeLa cells.

Defining the regulatory role of programmed cell death 4 in laryngeal squamous cell carcinoma.

Programmed cell death 4 (PDCD4) is decreased in many different kinds of malignant tumors. EMT endows tumor cells invasive and metastatic properties. However, few studies have determined the role of PDCD4 in the regulation of EMT in the context of laryngeal carcinoma. We examined the relationship between PDCD4 and EMT-associated proteins E-cadherin and N-cadherin using laryngeal carcinoma tissues. Gene manipulation was used to define the regulatory capacity of PDCD4. We report that PDCD4 and E-cadherin/N-cadherin expression were significantly changed in the carcinoma tissues, and their expression was associated with pathological grade, metastatic state, and clinical stage. The suppression of PDCD4 (and consequently, E-cadherin) was concomitant with increased proliferation and G2-phase arrest, decreased apoptosis, and increased cell invasion. PDCD4 upregulation reversed the above-mentioned results. In nude mice, PDCD4 knockdown increased tumor growth and pathological features, confirming the tumorigenic role of PDCD4. Finally, PDCD4 silencing was associated with dysregulation of the carcinogenic Wnt-ß-catenin and the STAT3-miR-21 signaling pathways. This study revealed a dynamic regulatory relationship between PDCD4 and critical factors for EMT, establishing a broad, functional role for PDCD4 in laryngeal carcinoma, which may be propagated by the STAT3-miR-21 pathway. These findings provide new information on an EMT-associated target that may lead to a novel therapy.

Review of pentosidine and pyrraline in food and chemical models: formation, potential risks and determination.

Pyrraline and pentosidine are advanced Maillard reaction products derived from the reaction of glucose with the lysine amino group on proteins. They have been implicated in uremia, diabetes, and related complications, including inflammation, retinopathy, and nephropathy. This review focuses on the formation mechanism, human potential risks, and detections of pentosidine and pyrraline and lays the foundation for further study of pentosidine and pyrraline. © 2017 Society of Chemical Industry.

The effect of pH and amino acids on the formation of methylglyoxal in a glucose-amino acid model system.

BACKGROUND: Methylglyoxal (MGO) as a α-dicarbonyl compound not only affects food flavor and color but also contributes to the loss of nutrition and the generation of toxic compounds. The study was carried out using a glucose-amino acid model system with incubation at 120 °C to investigate the effect of amino acids and pH on the formation of MGO. MGO derivative (2-methylquinoxaline) was detected by high-performance liquid chromatography with a diode array detector. Changes in glucose, amino acids and products such as acetic acid were tested using high-performance anion exchange chromatography with an electrochemical detector or an electrical conductivity detector. RESULTS: Lysine and glycine had higher reactivity to form MGO and melanoidins than arginine and proline. More acetic acid was produced and a higher consumption of arginine was observed in glucose-arginine solution. Moreover, higher pH significantly accelerated the formation of MGO. CONCLUSION: Amino reactivity and pH were two important factors affecting the formation of MGO in the Maillard reaction. © 2016 Society of Chemical Industry.

The functions of the Hippo signaling pathway in immune cells.

The Hippo signaling pathway, first identified in Drosophila, has emerged as a critical regulator for controlling the size of organs. Activation of the Hippo signaling pathway negatively regulates the Yorkie ortholog YAP in multiple organs, important in the regulation of cell proliferation, differentiation, and apoptosis during development. The Serine/Threonine protein kinases MST1 and MST2, mammalian homologs of the Drosophila Hippo kinase, play central roles in the Hippo signaling pathway in mammals. Recent studies reveal that non-canonical Hippo signaling pathways are also involved in the regulation of various other biological processes, particularly the important roles of MST1 and MST2 kinases in immune cell activation, adhesion, migration, growth, and apoptosis. In this review, we summarize the recent advances in understanding the roles of MST1 and MST2 kinases in the regulation of the functions of T lymphocytes and innate immune cells.

The effect of spray drying on sucrose-glycine caramel powder preparation.

BACKGROUND: Caramel is used as food colorant in many parts of the world. However, there have been no studies investigating the effects of spray drying on sucrose and glycine solutions. In this study, model sucrose and glycine solutions at different pH levels (pH 4, 3, 2 and 1) were treated with different inlet air temperatures (160, 180, 200, 220 and 240 °C) for durations of 50 s in the spray drying process. RESULTS: With increasing inlet temperatures and decreasing pH, the morphology of the caramel agglomerates tended to be more scattered; however, the solubility of the caramel decreased. With increasing inlet temperature, the glycine and sucrose contents decreased but the fructose and glucose contents increased. CONCLUSION: The content of the intermediate products, browning intensity and amount of 5-hydroxymethyl-2-furaldehyde (HMF) increased with increasing inlet temperature and decreasing pH. Therefore, the amount of sucrose degradation and the change in pH can be used to evaluate caramel properties in the spray drying process. © 2015 Society of Chemical Industry.

Short communication: Amino trap column improves the separation of methylimidazoles, 5-hydroxymethyl-2-furaldehyde, and sugars in Maillard reaction.

A simultaneous analysis of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde in the Maillard reaction was improved by use of an amino trap column. Analysis was carried out by using high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) coupled with an amino trap column. The amino trap column was a useful tool to improve the separation of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde. This technique is useful for simultaneous analysis of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde in risk assessment for dairy products.

Relationship between implantation of missing anterior teeth and oral health-related quality of life.

PURPOSE: The aim of the present study was to investigate the relationship between anterior teeth implantation and oral health-related quality of life (OHRQoL). METHODS: Participants completed the Chinese version of the Oral Health Impact Profile-14 (OHIP-14) prior to implantation and at 6 months following crown restoration. Participant demographic information was recorded. Six months following implant crown restoration, participants were asked to self-assess their overall oral health and implant restoration. A Kruskal-Wallis test and Spearman correlation test were used for statistical analyses. A p value <0.05 was considered statistically significant. RESULTS: A total of 238 patients (133 women and 105 men) completed the study. OHP-14 scores were negatively correlated with self-assessment of both overall oral health (r = -0.788, p < 0.001) and implant restoration (r = -0.739, p < 0.001) after implant crown restoration. There were no significant differences between qualitative reasons for dissatisfaction or between quantity of reasons given for dissatisfaction (p = 0.845). Six months following crown restoration, the overall OHIP-14 scores and the four common factors (disability, psychological discomfort, functional limitation, pain, and discomfort) decreased significantly compared to preimplantation scores (p < 0.001). From the paired differences between genders before and after implantation, significant differences were observed in overall quality (p = 0.044) and disability (p = 0.029). Patients with a higher education level scored significantly higher on overall quality of life (p = 0.031) and psychological discomfort (p = 0.002) following crown restoration. CONCLUSIONS: Our findings indicate that the implantation of anterior missing teeth could significantly improve patient OHRQoL. Gender and education level were shown to affect implantation results.

Simultaneous analysis of Nε-(carboxymethyl)lysine, reducing sugars, and lysine during the dairy thermal process.

A new analytical method allowing the simultaneous quantification of Nε-(carboxymethyl)lysine (CML), lysine, and reducing sugars (glucose, lactose, and galactose) is described. It is based on high performance anion-exchange chromatography with pulsed amperometric electrochemical detection. This method demonstrated a low limit of quantification (0.385 to 0.866 mg/L), excellent linear correlation (R(2)>0.997), and desired calibration range (3.125 to 25 mg/L). In addition, lactose-lysine solutions containing sulfite (4 to 400 mmol/L) were heated at 110°C for 2h. The results showed that sulfite inhibited the formation of CML and promoted the consumption of reducing sugars and lysine in the Maillard reaction model. The method proved to be useful for simultaneous analysis of CML, lysine, and reducing sugars (glucose, galactose, and lactose) in the Maillard reaction system. Moreover, sulfite was an effective inhibitor of CML formation.

Short communication: possible mechanism for inhibiting the formation of polymers originated from 5-hydroxymethyl-2-furaldehyde by sulfite groups in the dairy thermal process.

5-Hydroxymethyl-2-furaldehyde can undergo polymerization to form high-molecular weight molecules via the Maillard reaction during dairy thermal treatment. In this study, the effect of sulfite group on polymer formation, especially in inhibiting the formation of high-molecular weight polymers has been described. Results showed that the sulfite group significantly inhibited the increase of polymer molecular weight via prevention of the polymerization of 5-hydroxymethyl-2-furaldehyde. The formation of an intermolecular dimer based on the glucose molecule through Schiff base cyclization can lead to a competitive reaction with 1,2-enolization to reduce 5-hydroxymethyl-2-furaldehyde formation, which might be another factor in reducing the formation of high-molecular weight polymers.

[FTIR analysis of the impact of covalent coupling on the secondary structure of antibody protein].

The immunolatex was prepared by covalent coupling. FTIR technology combined with substractive spectroscopy, deconvolution, derivation and curve-fitting methods were used to study the structure of the antibody protein on the immunolatex. The result demonstrates that the alpha-helix strcture of antibody increases with the increase in the pH value and the concentration of latex. So it is concluded that covalent coupling has a great impact on the secondary structure of antibody protein.

[Interaction between latex microspheres and antibody proteins revealed by fluorescence spectroscopy].

Latex-antibody complexes were prepared by the method of covalent coupling and the properties of the complexes were studied by fluorescence spectrophotometric method for the purpose of revealing the interaction between latex microspheres and antibody proteins. Analysis of intrinsic fluorescence spectra showed that after being coupled with latex microspheres, the emission maximum of antibody protein showed an obvious blue shift, the intensity of emission maximum decreased significantly, the tertiary structure of antibody protein changed to some extent, the interaction between latex microspheres and antibody proteins had a great quenching effect on the intrinsic fluorescence spectra of antibody proteins, the quenching effect was enhanced along with the increasing pH value and latex concentration, and the quenching mechanism was static quenching. Results of exogenous fluorescence spectra showed that the fluorescence intensity of emission maximum was enhanced significantly after being coupled with latex microspheres, the hydrophobicity of antibody protein was decreasing with the increase in the pH values, however, due to the increasing latex concentration, the hydrophobicity antibody protein was increasing.

Primary Exploration of the Clinical Application of 3D-Printed Complete Dentures.

PURPOSE: To explore the applications of 3D scanning and 3D printing techniques in the restorative treatment of edentulous patients. MATERIALS AND METHODS: A total of 30 edentulous patients (Atwood classes 1 to 4) who visited The 960th Hospital of the People's Liberation Army, Jinan, China, from March 1, 2018 to May 1, 2020 were selected, and the patients were randomly divided into two groups: a traditional complete denture group (group A) and a 3D-printed complete denture group (group B). Each group comprised 15 patients. In group A, the traditional method was used to fabricate complete dentures. In group B, 3D scanning, computer-aided design (CAD), 3D printing, and the duplicate denture technique were used to fabricate the dentures. A single-blinded method was used. Patient satisfaction was measured with a 0-10 visual analog scale (VAS) at four time points: immediately and 1 month, 3 months, and 6 months after denture delivery. SPSS version 22.0 software was used to analyze the data. RESULTS: The ability to speak, ability to chew, and comfort in the two groups gradually improved at the first three time points. VAS scores increased to a satisfactory level after 3 months. The esthetics and stability of the two groups were scored high after the initial delivery. The VAS scores of the two groups regarding esthetics, ability to speak, ability to chew, stability, and comfort were not significantly different (P > .05) at any time point. The number of visits in the 3D-printed complete denture group were significantly decreased in comparison to the traditional group. CONCLUSION: The use of 3D printing for manufacturing complete dentures can rapidly restore edentulous patients and meet patient demands regarding esthetics and function.

[Fluorescence spectra analysis of whey protein isolate-dextran conjugate].

The mixed whey protein isolate (WPI)-dextran was treated by dry-heating to prepare Maillard reaction products (MRPs), which was characterized by the browning. The free amino groups content significantly decreased by 35.77% and 30.53% in glycated protein samples, as the molecular weight of dextran increased from 67 to 150 kD, respectively. This suggested that it was more difficult to be linked with WPI molecule when the chain length of dextran was increased. The characteristic of WPI-dextran conjugate was studied by fluorescence spectra in the paper. The maximum fluorescence intensity at 405 nm was obviously enhanced and G67 showed high fluorescence intensity than G150 over the wavelength range form 350 to 500 nm. This result revealed that the flourescent substance, a feature in Maillard reaction model system, was generated. As showed in the fluorescence spectra, the maximum fluorescence intensity at 470 nm was significantly decreased and the fluorescence intensity in each solution was in the order as follows: WPI>G150>G67. Moreover, the measurement of surface hydrophobicity index further showed that the hydrophobicity of WPI could be suppressed due to these two kinds of different molecular weight dextran.

Cytotoxic ergostane-type steroids from Ganoderma lingzhi.

Two new ergostane-type steroids (1 and 2) have been isolated from the fruiting body of a medicinal macro fungus Ganoderma lingzhi. The structures including the absolute configurations of them were elucidated by a combination of different spectroscopic analyses especially 13C NMR and ECD calculations. Compound 2 features an unusual 1,2-dioxolane moiety. Our bioassays revealed that the two steroids showed remarkable cytotoxicity against human A549 (lung) and MCF-7 (breast) tumor cell lines, with IC50 values ranging from 5.15 to 8.57 µg/mL.

Robust W/O/W Emulsion Stabilized by Genipin-Cross-Linked Sugar Beet Pectin-Bovine Serum Albumin Nanoparticles: Co-encapsulation of Betanin and Curcumin.

Betanin and curcumin hold promise as natural colorants and antioxidants for food purposes due to their anti-hypertensive, anti-inflammation, and anti-tumor effects. However, the thermal stability and bioavailability of betanin and curcumin still need improvement. Here, we fabricated sugar beet pectin-bovine serum albumin nanoparticles (SBNPs) with a mean particle size of 180 ± 5.2 nm through a genipin cross-linking strategy to stabilize a type of Pickering water-in-oil-in-water (W/O/W) emulsion and co-encapsulated betanin and curcumin. First, the W1/O emulsion was homogenized with gelatin (the gelling agent) in the water phase and polyglycerol polyricinoleate (a lipophilic surfactant) in the oil phase. Later, W1/O was homogenized with another water phase containing SBNPs. The microstructure of the emulsion was regulated by the particle concentration (c) and W1/O volume fraction (Φ), especially the gel-like high internal phase emulsions were formed at the Φ up to 70%. In this case, betanin was encapsulated in the internal water phase (encapsulation efficiency = 65.3%), whereas curcumin was in the medium-chain triglyceride (encapsulation efficiency = 84.1%). Meanwhile, the shelf stability of betanin and curcumin was improved. Furthermore, the stability of bioactive compounds was potentiated by an emulsion gel in simulated gastrointestinal digestion, resulting in higher bioaccessibility. The aforementioned results suggest that SBNP-stabilized Pickering W/O/W emulsions could be a potential alternative to co-encapsulate betanin and curcumin with enhancement of shelf stability and bioaccessibility.